blankman



(No Model.) I 2 Sheets-Sheet 1. J. S. BLANKMAN. TUBULAR GUN SIGHT.

Patented Dec. 3, 1.889.

2 a e h S b m S .N A M K N A L B S J TUBULAR GUN SIGHT.

Patented Dec. 3, 1.889.

INVENTOR v QJJ showing a modification of sight-pins.

I UNITED STATES PATENT OFFICE.

JOHN S. BLANKMAN, OF WASHINGTON, DISTRICT OF COLUMBIA.

TUBULAR GUN-SIGHT.

SPECIFICATION forming part of Letters Patent No. 416,554., dated December 3, 1889.

Application filed July 31, 1889. Serial No. 319,293- (No model.)

To all whom it may concern.-

Be it known that I, 'JoHN S. BLANKMAN, a

resident of Washington, in the District of Columbia, have invented certain new and useful Improvements in Gun-Sights; and I do hereby declare the following to be a full,

clear, and exact description of the invention,

such as will enable others skilled in the art to which it pertains to make and use the same.

The object of the invention is a gun-sight tube adapted to varying conditions and re-' quirements, and it is an improvement upon a side elevation, partly in section, of. an extensible or compound gun-sight tube attached to a gun-barrel. Fig. 2 is an enlarged'transverse section on the line 00 x of Fig. 1. Figs.

3, 4, 5, 6, 7, and 8 are cross-sections of different forms of one part of the compound sighttube, Fig. 8 being on an enlarged scale and Fig. 9 is a' similar enlarged view indicating cross wire or hairs, and also a special arrangement of the inner part of the compound sighttube. Fig. 10 is a longitudinal section of one form of the main or larger part of the compound tube, the dotted lines indicating diagrammatically the use of sight-notches for various ranges. Fig. 11 is a top plan view of the same, and Figs. 12 and 13 are respectively longitudinal and transverse sections of a modification of a part of the tube shown in Figs. 10 and 11. Fig. 14 is a transverse section of the tube and base-piece in the region of the key and stop. Fig. 15 is a side elevation, partly in section; and Fig. .16, a sectional plan of my improvement applied to a gun.

The sight-tube is composed of the part 1, which maybe secured to a gun-barrel in any usual or preferred way, but which in the present instance is shown as secured in a base 5, having a dovetail key' 3, of usual form, fitting transversely in a similarly-shaped slot in the barrel. f This dovetail piece, however, is preferably provided witha novel device or stop 4, shaped to conform to :the surface of the barrel and designed to locate and hold the lock or key 3 in its proper lateral position. This tube 1 may be secured in the base-plate by a lengthwise dovetail connection-such as indicated at 9 in Fig. 2-or a construction similar to that indicatedjn Fig. 3 may be substituted, such figure showing means for connecting a tube 2 direct to a base provided with a dovetail lock or key of customary form.

The tube may be connected to the base plate or to the barrel by any convenient arrangement of keys or flanges, substantially such as indicated.

2 is a tube made of a form and size to fit within the tube 1 and be movable therein with sufficient friction to retain any desired position longitudinally.

Each part of the compound tube is prefer- .ably provided on one side with an opening or and is adjusted lengthwise to make the compound tube longer or shorter, as desired, it being understood that the longer the extensible tube is made the smaller will be the field of vision.

The invention is not limited to the use of two tubes, as a larger number fitting each other telescopically may be employed, if desired, or the tubes 1 and 2 may be separated and either used alone.

The tube 2, as represented in Figs. 1 and 2, has its slotted side uppermost, as is the case with tube 1; but if it is desired to exclude a part of the light which ordinarily enters these slots tube 2 can be partially turned and inserted, as indicated in Fig. 9; and it is obvious that the inner tube might be still further turned so that its flanged side 11 would close the openings 6 in tube 1, which might be advisable under different circumstances either to exclude light or moisture.

The tube 2 may have various forms in cross-section, and in some modificationssuch, for example, as illustrated in Figs .1, 2, 5, 7, and 8may be stamped out of sheet metal, as also may be tube 1.

According to the arrangement illustrated in Fig. 9, as will be seen, the inner tube does like spaces between them at 13 13. These spaces are adapted to aid the marksman in approximating a central line of sight through the inner tube; or in case of high wind the sight obtained through these outer tubular spaces may be used for directing the firing.

In Figs. 10 to 16 is indicated an additional sight device applied to tube 1, which consists in a notch 12 in a cross-bar 15, which latter constitutes a part of the upper side of the tube, and which device is adapted for use in long ranges, as diagrammatically denoted by means of the dotted lines. Thus for an ordinary range the line of sight will pass through the tubes near an axial line; but for a long range, requiring an elevation of the muzzle of the gun, the construction is such that the line of sight after entering the forward end of the tube will pass out through its open top, and the construction is such that the correct sight will be indicated by the first ray that passes from the mark through the notch to the eye, and these notches may be arranged to correspond with ranges of various extent, so as to indicate their length-11 6., the distance of the mark. These notches can be used in the double or compound tube above described, and the pins 8 will be useful for short ranges, and the notches in combination with a front or muzzle sight for longer ones.

The sight-pins are doubled or branched, as shown in Figs. 1 and 2 and in a modified form in Fig. 8. The advantage of this form of pin is that when the mark is viewed between its two adjacent parts any deviation from a straight line passing from the mark or the muzzle-sight to the eye between said parts begins to be visible at the commencement of such variation, while in case of solid pins arranged exactly in the line of vision a material variation must occur before it is perceived; The functions of the notches 12 are, however, independent of sight-pins.

Instead of several cross-bars, (indicated in Figs. 10 and 11,) one adjustable one may be employed, as illustrated in Figs. 12 and 13, and one or more of the cross-bars may be notched on both sides.

My sight-tube is distinguished from amere sight-protectorsuch as a ring or short tube located near the gun-muzzlein respect to its location, form, and functions. It is placed to the rear of the front sight and is made in the form of a tube of considerable length, its general function being to confine or limit the field of vision, and it ordinarily consists of two members, one of which slides within the other in such manner as to leave several sight tubes or passages between them, and arranged so as to provide, when desired, for an extension of the compound tube, and so, also, as to provide for obscuring more or less the light-openings by various arrangements of the tubes in transverse direction.

The flange provided on the key has special relation to my tube-sight and prevents the latter from being moved out of the proper line laterally by a slight pivotal or rotary movement of the key in case it or its seat has become worn or in case the original fit was not tight. While such a movement in an ordinary sight-pin would be of no practical consequence, it is important to obviate it in the case of a long sight-tube, and this device is intended to prevent any tendency, however slight and under whatever conditions, in the sight-tube and its key toward turning laterally in the key-seat.

My invention is further to be distinguished from sights which embrace a short tube fitted to a tubular seat, but not adapted to be adjusted lengthwise therein to vary the length of the sight-tube nor adapted to be adjusted to form several sight-passages parallel to the' axis of the tube.

Having thus described my invention, what I desire .to secure by Letters Patent is as follows:

1. In combination with a gun, a muzzlesight and a rear-sight tube having unobstructed light-openings in its side, substantially as described.

2. In combination with a gun and a muzzle-sight, the rear-sight tube having an unobstructed opening in one of its sides, the edge of the material at the end of said opening and bounding the same being provided with a notch located in a plane passing through the line of sight, substantially as described.

3. In combination with a gun, a muzzlesight and a compound tube having two members, one normally sliding within the other and adapted to vary the length of the compound tube, substantially as described.

4.. In combination with a gun, a sight-tube consisting of two members normally sliding one within the other, said tubes being dissimilar in cross-section and the interior tube touching the inner surface of the outer tube along several longitudinal lines to produce several sight-passages parallel to the axis of the tube, substantially as described.

5. In combination with a gun, a compound tube having two members, one sliding within the other and adjustably held therein, each provided with a light-opening in its upper side, substantially as described.

6. A compound sight-tube having two members, one sliding within the other, each provided with alight-opening in one of its sides, the inner tube being adapted to enter the other with either of its sides adjacent to the open side of the outer tube, substantially as described.

7. In combination with a gun and with a muzzle-sight, a rear-sight tube provided with a double or notched sight-pin, substantially as described.

8. In a sighting device, the combination of a rear sight-tube with a muzzle-sight and with a key for securing the sight-tube to a In testimony whereof I have signed this 10 specification in the presence of two subscribing witnesses.

JOHN S. BLANKMAN.

Witnesses:

JOHN T. MITCHELL, H. J. MAY. 

